JPH08329505A - Optical pickup - Google Patents

Abstract

PURPOSE: To provide an optical pickup with less fluctuation in a track signal due to de-focus and with stable playability. CONSTITUTION: Light outgoing from a laser module 1 is diffracted/converged by an optical system such as an incident part 11, a reflection part 13 and a convergence part 14, etc., and a recording surface of an optical disk 4 is irradiated by the light, and the reflected light is made incident on the laser module 1. In the optical pickup, the incident part 11, the reflection part 13 and the convergence part 14 are integrated to be made an optical unit 10, and the optical unit 10 is assembled in the interior of a bobbin 16, and the laser module 1 is assembled to the side part of the bobbin 16. When an actuator coil 8 is energized, the optical unit 10 and the laser module 1 are displaced integrally without shifting optical axes, and focusing and tracking are performed. Further, the pickup is thinned by assembling the optical unit 10 in the inside of the bobbin 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for recording / reproducing data on / from a CD-ROM, a magneto-optical disk, a phase change disk or the like.

[0002]

2. Description of the Related Art In order to reduce the cost of an optical pickup,
A laser module in which a semiconductor laser, an optical path separating unit for separating light from the semiconductor laser and reflected light from the optical disk, and a plurality of light receiving elements for receiving light from the optical disk are integrated has been put into practical use. There is. By integrating the optical system in this way, the optical system of the optical pickup can be configured by the three points of the laser module, the raising mirror and the objective lens, and the number of assembling steps and the cost can be reduced.

A conventional optical pickup using a laser module will be described below. FIG. 3 is a block diagram of a conventional optical pickup. A semiconductor laser is mounted on the laser module 1, and the light emitted from the semiconductor laser is emitted from the laser module 1 through an optical path separating unit such as a hologram. The emitted light has its optical path bent substantially orthogonally by the rising mirror 2 and is condensed by the objective lens 3 to form a spot on the recording surface of the optical disc 4. The reflected light from the optical disk 4 again passes through the objective lens 3 and the rising mirror 2 and enters the laser module 1. The laser module 1 has optical path separating means, and the optical disk 4
The focus detection function based on the well-known Foucault method operates for the reflected light from the. Track detection is performed by the known three-beam method. The output signal from the light receiving element in the laser module 1 drives the actuator coil 8 through the operational amplifier 5 and the actuator drive amplifier 6 to focus and track the objective lens 3. Here, the objective lens 3 is adhesively fixed to the bobbin 9.

[0004]

Since the actuator coil 8 for focusing and tracking the objective lens 3 needs to have a predetermined size, the bobbin 9 is larger than the objective lens 3. However, in the conventional configuration, since only the objective lens 3 is assembled to the bobbin 9 and the raising mirror 2 is further separated from the body, there is a problem that the optical pickup cannot be made thin,
Since the objective lens 3 and the raising mirror 2 are not one component, there is a problem that the cost is high.

Therefore, an object of the present invention is to provide a thin and low cost optical pickup.

[0006]

To this end, the present invention provides a laser module having a semiconductor laser for emitting light,
An optical pickup comprising: an optical system that refracts the light emitted from the semiconductor laser toward the optical disc side, irradiates the recording surface of the optical disc in a spot manner, and refracts the reflected light to enter the laser module. An incident unit, a reflection unit, and a condensing unit that form the optical system are integrated into an optical unit, and the optical unit is assembled inside the actuator movable unit, and the laser module is provided on a side of the actuator movable unit. By assembling, the optical unit and the laser module can be integrally moved.

[0007]

According to the above structure, by driving the movable portion of the actuator, the optical unit and the laser module can be integrally displaced to perform focusing and tracking, and the optical axis and the laser module are deviated from each other. Absent. Further, the incident portion, the reflecting portion, the condensing portion, and the like are integrated to form an optical unit, which is attached to a bobbin of the actuator movable portion, so that the optical pickup can be made thin.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an optical pickup according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of an optical axis shift when the reflecting and converging means is driven. A semiconductor laser is mounted on the laser module 1. Reference numeral 10 denotes an optical unit, which includes an incident portion 11 on which light emitted from the semiconductor laser is incident,
A reflecting portion 13 that raises and reflects the light incident on the incident portion 11 and a condensing portion 14 that condenses the light reflected by the reflecting portion 13 and emits the light toward the optical disc are integrated. . The incident surface of the incident portion 11 is an aspherical surface 12,
The exit surface of the condenser 14 is also an aspherical surface 15. Therefore, the light emitted from the semiconductor laser is refracted by the aspherical surface 12 of the incident portion 11, the optical path is bent substantially orthogonally by the reflecting portion 13, is condensed by the condensing portion 14, and then is aspherical surface 15.
And emitted onto the recording surface of the optical disc 4 in a spot-like manner. The reflection from the optical disk 4 passes through the optical unit 10 again and enters the laser module 1. The optical unit 10 is assembled inside the bobbin 16,
The laser module 1 is mounted on the side of the bobbin 16. Therefore, the optical unit 10 and the laser module 1 are integrally movable.

The laser module 1 has an optical path separating means (hologram), and a focus detection function based on the well-known Foucault method works on the reflected light from the optical disk 4.
Track detection is performed by the known three-beam method.
The output signal from the light receiving element in the laser module 1 drives the actuator coil 8 through the operational amplifier 5 and the actuator drive amplifier 6. Then the optical unit 1
0 and the laser module 1 are displaced integrally, and focusing and tracking are performed.

If only the optical unit 10 is displaced during focusing and tracking, the optical axis of the laser module 1 is displaced with respect to the laser module 1 as shown in FIG. In this case, since the movable range of focusing is ± 0.7 mm, the off-axis coma aberration generated in the lens becomes large, which causes a problem that a good spot cannot be formed. However, in the present embodiment, as shown in FIG. 1, the laser module 1 is also adhesively fixed to the bobbin 16 to be integrated with the optical unit 10 so that the optical axis shift can be eliminated.

[0011]

As described above, according to the present invention, the optical system such as the incident part, the reflecting part, and the condensing part is integrated to form an optical unit, which is assembled to the actuator movable part, so that the optical pickup can be made thin. Moreover, the number of parts can be reduced to reduce the cost. Also, by integrating the optical unit and the laser module, stable recording / reproducing can be realized without any deviation of the optical axis during focusing or tracking.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical pickup according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an optical axis shift when driving a reflecting and converging unit according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional optical pickup.

[Explanation of symbols]

 1 Laser Module 4 Optical Disc 8 Actuator Coil 10 Optical Unit 11 Incident Part 13 Reflector 14 Condenser 16 Bobbin

Claims (1)

[Claims] 1. A laser module equipped with a semiconductor laser for emitting light, and light emitted from this semiconductor laser is refracted toward the optical disc side to irradiate the recording surface of the optical disc spotwise and refract the reflected light. And an optical system for making the laser module incident on the laser module, wherein an incident part, a reflecting part, and a condensing part forming the optical system are integrated into an optical unit, and the optical unit is an actuator moving part. The optical pickup is characterized in that the optical unit and the laser module can be integrally moved by assembling the laser module on the side of the actuator movable portion while assembling the inside of the laser module.